Field of the Invention
The present invention relates to a display device, and more particularly, to a high efficiency reflector which reflects multiple color light, and to a display device which can increase display quality by applying the high efficiency reflector thereto.
Description of the Related Art
Electrophoretic display devices denote devices that display an image with electrophoresis in which colored charged particles move by an electric field given from the outside. Herein, electrophoresis denotes an electrophoretic motion where with charged particles being dispersed into a solvent, the charged particles moves inside the solvent by Coulomb force when applying an electric field.
Electrophoretic display devices using electrophoresis have bistability, and thus can maintain a displayed image for a long time even when an applied voltage is removed. That is, since electrophoretic display devices maintain a constant screen for a long time even when a voltage is not continuously applied thereto, the electrophoretic display devices are display devices suitable for an e-book field that does not require the quick change of a screen.
Also, electrophoretic display devices are not dependent on a viewing angle unlike Liquid Crystal Display (LCD) devices, and moreover, provide an image comfortable for eyes by the degree similar to papers because reflecting external light to display an image. Furthermore, electrophoretic display devices have flexibility, low power consumption, and eco like. Accordingly, the demand of electrophoretic display devices is increasing.
FIG. 1 is a sectional view illustrating a related art electrophoretic display device.
Referring to FIG. 1, the related art electrophoretic display device includes a lower substrate 10 and an upper substrate 20 that are facing-coupled to each other, and an electrophoretic film 30 disposed between the lower substrate 10 and the upper substrate 20.
The lower substrate 10 includes a plurality of pixel electrodes (not shown), and a plurality of thin film transistors (TFT, not shown) for respectively applying a voltage to the pixel electrodes.
A common electrode 22 is formed at the upper substrate 20.
The electrophoretic film 30 includes a plurality of microcapsules 32 that are formed of charged particles and a solvent, and an adhesive layer 34 that protects the microcapsules 32 and is adhesive to the lower substrate 10.
Herein, each of the microcapsules 32 includes positive charged particles, negative charged particles, and a solvent that surrounds each of the positive and negative charged particles.
When an electric field is generated between the pixel electrode of the lower substrate 10 and the common electrode 22 of the upper substrate 20, the charged particles included in the microcapsules 32 move toward the upper substrate 20 or the lower substrate 10 by electrophoresis, thereby realizing an image.
The lower substrate 10 that is formed through a separate process, the upper substrate 20 that is formed by a separate process different from the formation process of the lower substrate 10, and the electrophoretic film 30 that is adhered to the upper substrate 20 by a lamination process are manufactured separately, and then by coupling the two substrates 10 and 20, the related art electrophoretic display device is completed.
Herein, the electrophoretic film 30 is managed and conveyed, with the electrophoretic film 30 being adhered to the upper substrate 20. Afterward, the passivation layer adhered to the adhesive layer 34 is removed from the upper substrate 20 with the electrophoretic film 30 adhered thereto so as to expose the adhesive layer 34. By coupling the upper substrate 20 and the lower substrate 10 through the adhesive layer 34, the electrophoretic display device is completed.
In the related art electrophoretic display device, since the lower substrate 10, upper substrate 20, and electrophorectic film 30 are manufactured separately, a manufacturing process is complicated, and much time is taken in manufacturing, causing the decrease in manufacturing efficiency. Also, it is difficult to accurately arrange the upper substrate 20 and the lower substrate 10, and a failure occurs.
Moreover, the related art electrophoretic display device displays an image by using the reflection of external light, but has a low contrast ratio and a low color reproduction ratio because the light reflection efficiencies of the microcapsules 32 are low.
To solve such limitations, a structure was proposed where a metal reflector is formed on a lower substrate and thus increases a light reflection rate, but in the structure, since a plurality of parasitic capacitors are formed between the reflector and the pixels of the lower substrate, the parasitic capacitors exert a bad influence on the driving of the pixels.
In applying the metal reflector of the related art, in order not to affect the driving of an active matrix of pixels, the related art requires a patterning process and a process that deposits a metal material over the metal reflector.
The metal reflector of the related art reflects only 40% of incident light, and thus has limitations in increasing luminance, a contrast ratio, and a color reproduction ratio.